Thursday, 10 August 2017

I came across this interesting article in WSJ, courtesy of the Benedict Evans newsletter, which discusses how Indians are using their smartphones even more and consuming far more data than they previously did. Due to low incomes, spending money on mobile top-up is to the detriment of other sectors. To quote the article:

“There was a time when kids would come here and blow their pocket money on chips and chocolate,” said Anup Kapoor, who runs a mom-and-pop grocery shop in New Delhi. These days, “they spend every last rupee on a data recharge instead.”

United Nations have created 17 very ambitious Sustainable Development Goals (SDGs) that universally apply to all, countries will mobilize efforts to end all forms of poverty, fight inequalities and tackle climate change, while ensuring that no one is left behind.

The SDGs, also known as Global Goals, build on the success of the Millennium Development Goals (MDGs) and aim to go further to end all forms of poverty. The new Goals are unique in that they call for action by all countries, poor, rich and middle-income to promote prosperity while protecting the planet. They recognize that ending poverty must go hand-in-hand with strategies that build economic growth and addresses a range of social needs including education, health, social protection, and job opportunities, while tackling climate change and environmental protection.

I have talked about Rural connectivity on this blog and a lot more on small cells blog. In fact the heart touching end user story from Rural England was shared multiple times on different platforms. GSMA has done a good amount of work with the rural communities with their mobile for development team and have some interesting videos showing positive impacts of bringing connectivity to rural communities in Tanzania (see here and here).

Coming back to the first story of this post about India, when given an option about selecting mobile data or shampoo, people will probably choose mobile data. What about mobile data vs food? While there are some innovative young companies that can help bring the costs down, there is still a big hurdle to leap in terms of convincing the operators mindsets, bureaucracy, etc.

To help explain my point lets look at an excerpt from this article in Wired:

It’s the kind of problem that Vanu Bose, the founder of the small cell network provider CoverageCo, has been trying to solve with a new, ultra-energy-efficient mobile technology. Bose chose two places to pilot this tech: Vermont and Rwanda. “We picked these two locations because we knew they would be challenging in terrain and population density,” he says. “What we didn’t expect was that many of the problems were the same in Rwanda and Vermont—and in fact the rollout has been much easier in Africa.”

The good news is that things are changing. Parallel Wireless (see disclosure at the bottom) is one such company trying to simplify network deployment and at the same time bring the costs down. In a recent deployment with Ice Wireless in Canada, this was one of the benefit to the operator. To quote from MobileSyrup:

A radio access network is one of the key components in the architecture of any wireless network. RANs sit between consumer-facing devices like smartphones and computers and the core network, helping connect those devices to the larger network.

Essentially where the likes of Nokia and Huawei ask clients to buy an expensive hardware component for their RAN needs, Parallel Wireless offers allows companies like Ice Wireless to use off-the-shelf computer and server components to emulate a RAN. The company also sells wireless base stations like the two pictured above that are smaller than the average cell tower one sees in cities and less remote parts of the country.

Besides reducing the overall price of a network deployment, Parallel’s components present several other advantages for a company like Ice Wireless.

For instance, small base stations make it easier for the company to build redundancies into its network, something that’s especially important when a single arctic snowstorm can knock out wireless service for thousands of people.

These kind of benefits allow operators to pass on the cost reduction thereby allowing the price reduction for end users. In case of Ice Wireless, they have already got rid of roaming charges and have started offering unlimited data plans for the communities in Canada's North.

Achieving the SDGs demands new technologies, innovations, and data collection that can integrate and complement traditional statistics. A driving force behind this data revolution is mobile technology.

As we focus on implementing the Sustainable Development Goals, the mobile industry has a critical role in working with governments and the international community to expand connectivity, to lower barriers to access, and to ensure that tools and applications are developed with vulnerable communities in mind.

With 5G just round the corner, I hope that the operators and vendors will be able to get their costs down, resulting in lower end-user prices. That would be a win-win for everyone.

*Full Disclosure: I work for Parallel Wireless as a Senior Director, Strategic Marketing. This blog is maintained in my personal capacity and expresses my own views, not the views of my employer or anyone else. Anyone who knows me well would know this.

Monday, 9 June 2014

From the 1st of July 2014, the new EU Roaming Regulations III will become active.

The new EU Roaming regulations set by the European Commission, will allow retail mobile customers to purchase roaming services (such as voice, SMS and data) from an Alternative Roaming Provider (ARP) separate from their domestic service provider (DSP), without affecting either mobile number or device.

The general idea behind the regulations is to promote the interests of European citizens by increase competition between European operators, provide greater transparency, reduce bill shocks, and ultimately provide a greater roaming experience and higher quality of service for consumers.

European Commission President Jose Manuel Barosso said in a press release:

“Further substantial progress towards a European single market for telecoms is essential for Europe’s strategic interests and economic progress. For the telecoms sector itself and for citizens who are frustrated that they do not have full and fair access to internet and mobile services.”

Vice President Neelie Kroes, the Digital Agenda Commissioner responsible for package then continued in the same press release by saying:

“The legislation proposed today is great news for the future of mobile and internet in Europe. The European Commission says no to roaming premiums, yes to net neutrality, yes to investment, yes to new jobs. Fixing the telecoms sector is no longer about this one sector but about supporting the sustainable development of all sectors.”

Requirements

The process of selecting an ARP and its services while abroad within EU is more commonly known as decoupling or separate sale of roaming services. BEREC (the body of European Regulators for Electronic Communications) have provided the European Commission with their recommendations of two decoupling models that should be supported; Local breakout (LBO, which is the local provisioning of data services by a visited network operator, or Single IMSI solution where the ARP acts as a reseller of the DSPs service offerings.

Decoupling using Single IMSI

With the Single IMSI solution the ARP will engage in agreements with each domestic operator providing domestic services, then the ARP will act as a reseller of these services to the roaming subscriber. This type of solution is applicable for all types of service providers such as mobile network operators, MVNOs or VSPs. From a subscriber standpoint, they will have a roaming agreement with the ARP regardless of the DSP and the DSP is required to activate services within one working day.

Decoupling using Local Breakout

The Local breakout model refers to local provisioning of data services only, where the services is provided directly on the visited network and traditional SMS and voice traffic is supplied by the home operator in traditional roaming manner. By using the 3GPP option for local breakouts, the VPMN will be able to act as ARP for internet access and other data services.

With these new regulatory changes, there is a higher demand on flexibility in billing systems. Support for more complex multi-partner business models for ARP and MVNO is necessary for both billing and financial settlement activities.

Raymond Bouwman from Rabion Consultancy did an excellent presentation last year in the LTE World Summit, here is his presentation explaining more about the EU Roaming Regulations III

Tuesday, 1 April 2014

A new video and simplified presentation on this topic is available on 3G4G page here.

It took me quite a while trying to understand the different types of operators and the differences between them. Here is a short summary. Please feel free to add more information or correct me where needed

Mobile Network Operator (MNO): The MNO is the most commonly visible mobile network operator. Examples would be the likes of Vodafone, Verizon, T-Mobile, Orange, Telefonica, etc. These MNO's are responsible for creating the mobile network. They have to purchase/lease the spectrum from the regulatory body of the country and then purchase/lease the network equipment from the vendors. They have to then get into an agreement with various handset suppliers, do various testing, etc. They are responsible for the day to day running of the network and would be blamed if there are problems or if the quality of experience is not as expected.

The MNO has to maintain its own Operation Support Systems (OSS) and Business Support Systems (BSS). They are responsible for billing the direct customers and may also be responsible for indirectly billing the customers of MVNO's.

Mobile Virtual Network Operator (MVNO): An MVNO relies on the infrastructure and most other things provided by the MNO. The MNO may have plenty of spare capacity that it may be willing to sell at a cheaper price or a different rate. They wouldn't want to do this themselves as this may dilute the brand. To solve this they may sell the messages, voice minutes and data at a much cheaper price in wholesale to an MVNO. Examples of popular MVNO's include Virgin Mobile, Lyca Mobile, Walmart mobile, Lebara Mobile, etc.

A full fledged MVNO will have its own OSS/BSS software and would be responsible for billing its own customers but a smaller MVNO may rely on the MNO to provide usage information for its customers that it can bill.

Mobile Virtual Network Aggregator (MVNA): Sometimes, it makes little or no sense to have many small MVNO's connected to the MNO. As a result, MNO may decide to only sell the discounted bundles to really big players. An MVNA can aggregate lots of small MVNO's and using the collective might, be able to connect to the operator as a single MVNO. MVNA's will typically not have direct subscribers but only other smaller MVNO's that connect to it. It would typically have to have an own OSS/BSS to be able to provide accurate billing information to the MVNO's.

Mobile Virtual Network Enabler (MVNE): An MNO may decide to outsource all functionality related to virtual networks to an MVNE. The MVNE may do similar functionality like an MVNA or it may even allow MVNA to connect to the MNO via itself. It may allow MVNO's to connect to MNO's through it and in special cases, it may even provide sell services directly to customers. The main reason for it being called an Enabler is because its enables smaller MVNO's to be created. It can provide services to such as billing, network element provisioning, administration, operations, support of OSS/BSS, etc. to MVNOs. An MVNE typically would not have any relationship with end-user customers, instead focussing on providing infrastructure and services to enable MVNO's to offer services and have a relationship with end-user brand, customer loyalty and marketing and leave the back-end enablement to MVNE's.

The MVNO's could be Full or Light MVNO's. The above picture shows different variants but in simple terms a Full MVNO has its own HLR while the Light(er) MVNO's use the HLR of the MNO where it enters the details of its own subscribers. A Full MVNO has considerably more power as it may decide to move to another MNO for service if its not happy with the service provided by an MNO. It would definitely also mean a lot more investment as opposed to the lighter models.

Sometimes MVNOs refer to themselves as Skinny, Thin or Thick as can be seen in the picture above. My guess is that its just another term for Full, Light or Branded resellers.

Finally, we may be in what is being termed as MVNO 3.0. As per this PwC article:

The first generation of MVNOs was spawned during an era of regulatory concerns and rapid growth in the wireless industry. They struggled to compete with the very network owners who were selling them capacity. The second generation, known in some circles as MVNO 2.0, sought to change the playing field by basing customer relationships on innovative devices such as the iPhone and the Jitterbug. Could we be witnessing the end of the era of the branded network operator? Here are four key changes currently underway that could make MVNO 3.0 a reality.

Finally, if you have enough time and patience, there is an interesting list of articles to read on this topic.

Thursday, 30 January 2014

I had been having some discussions regarding Multi-SIM phones and there is a bit of misunderstanding so here is my clarification about them. Anyway, a lot of information is just an understanding so feel free to correct any mistakes you think I may have made.

This post is about multiple SIM cards, physical UICC cards rather than single UICC with multiple SIM applications. We will look at Dual IMSI later on in the post. In case you do not know about the multiple SIM applications in a UICC, see this old post here. In this post, I will refer to UICC cards as SIM cards to avoid confusion.

Back in the old days, the Dual-SIM phones allowed only one SIM on standby at any time. The other SIM was switched off. If someone would call the number that was switched off, a message saying that the number is switched off would come or it would go in the voicemail. To make this SIM in standby, you would have to select it from the Menu. The first SIM is now switched off. The way around it was to have one SIM card calls forwarded the other when switched off. This wasn't convenient and efficient, money wise. The reason people use multiple SIM phones is to have cheaper calls using different SIMs. So in this case forwarding calls from one SIM to another wont be cost effective. These type of phones were known as Dual SIM Single Standby or DSSS. These devices had a single transceiver.

So as the technology got cheaper and more power efficient, the new multi-SIM devices could incorporate two receivers but only one transmitter was used. The main reason being that using two transmitters would consume much more power. As a result, these devices can now have both the SIM's on standby at the same time. These kind of devices were known as Dual SIM Dual Standby or DSDS. Wikipedia also calls then Dual SIM Standby or DSS. This concept could be extended further to Triple SIM Triple Standby or TSTS in case of the device with three SIM cards and Quad SIM Quad Standby or QSQS in case of four SIM cards. One thing to remember is that when a call is received and a SIM becomes active, the other SIM cards become inactive for the duration of the call. A workaround for that situation is to forward the call to the other SIM card in case if its unavailable. Though this will work for DSDS, it may not be that straightforward in case of TSTS and QSQS due to more than two SIM cards being present.

Another category of devices that are now available are the Dual SIM Dual Active or DSDA. In this case there are two transceivers in the device. Both the SIM cards are active at the same time so each SIM card can handle the call independently of each other. It would even be possible to conference both these calls.

With the prices of calls falling, there is no longer a real need for multiple SIM cards. One SIM card is generally sufficient. It may be useful though to have multiple IMSI on the SIM card. The different IMSI would have different country and network code. For example, a person in in UK can have one IMSI with the home network code and one with say a US operator IMSI. This IMSI could only be programmed by the home operator. When the person is in UK he could receive calls on his UK number or on the US number which would be routed to his UK number. For a person in US calling the US number, this is a national call rather than an international one. When the person is roaming in the US, his US IMSI would behave like non-roaming case while the calls to the UK number would be forwarded to the US number.

Sunday, 30 June 2013

Recently got another opportunity to hear from Andy Sutton, Principal Network Architect, Network Strategy, EE. His earlier presentation from our Cambridge Wireless event is here. There were many interesting bits in this presentation and some of the ones I found interesting is as follows:

Interesting to see in the above that the LTE traffic in the backhaul is separated by the QCI (QoS Class Identifiers - see here) as opposed to the 2G/3G traffic.

This is EE's implementation. As you may notice 2G and 4G use SRAN (Single RAN) while 3G is separate. As I mentioned a few times, I think 3G networks will probably be switched off before the 2G networks, mainly because there are a lot more 2G M2M devices that requires little data to be sent and not consume lots of energy (which is an issue in 3G), so this architecture may be suited well.

Finally, a practical network implementation which looks different from the text book picture and the often touted 'flat' architecture. Andy did mention that they see a ping latency of 30-50ms in the LTE network as opposed to around 100ms in the UMTS networks.

Friday, 31 May 2013

The same old story, mobile operators are seeing that their revenue is not growing, even though they are upgrading their networks and introducing new features / technologies. The following is from Total Telecom:

The global telecom services market generated revenue of €1.12 trillion in 2012, although at 2.7% growth was slower than in the previous year, according to the 2013 DigiWorld Yearbook published by IDATE on Thursday.

The "DigiWorld" as a whole - which also includes telecoms hardware, software and computer services, computer hardware, TV services, consumer electronics and Internet services – recorded revenues of €3.17 trillion last year, up 2.8% on 2011. By 2016 that figure will have risen to €3.66 trillion, IDATE predicts, with telecoms services contributing €1.25 trillion (see chart).

Telecoms operators are experiencing flat growth, while over-the-top (OTT) providers are seeing revenues increase by 15% a year, Vincent Bonneau, head of IDATE's Internet business unit, told attendees at the DigiWorld Yearbook launch in London earlier this month.

Another interesting piece of news was that Viber has launched a desktop application which means it can now rival Skype fully.

Guess what, I would think that operators have more to worry from this news than Skype. I have stopped using Skype for some time now due to many issues I have with it and have moved to Viber for a few months. If you are a regular reader to this blog then you would have read my recent post complaining about the global roaming rates. When I am travelling abroad, I make sure there is WiFi and use Viber as a substitute for Voice and SMS. In fact I can send MMS and emoticons using Viber which would cost a fortune over cellular otherwise.

Sometimes it feels like the operators are sleepwalking into their own destruction by not innovating enough and fast to be a challenge for these OTT services. Not entirely sure what the solutions are but there are quite a few ideas around to start thinking in that direction. An interesting presentation by Dean Bubley I posted here is a good starting point. Another one from him and Martin Geddes is embedded below, which is quite interesting and intutive.

@o2 @ronandunneo2 O2 in the USA: £6 per meg. Vodafone in the USA: £25 for 100 meg a day. Sorry, but that's an easy choice.
— Benedict Evans (@BenedictEvans) May 18, 2013

Those who follow me on Twitter may have noticed me ranting about the roaming prices recently so I thought that this is a perfect opportunity to put my thoughts down.

As being discussed above, I went on the websites of two UK operators and found out about their roaming rates to India and The USA and they are as follows:

It should be noted that there is a better rate available with some kind of bundle opt-in from both the operators and I have not shown about the other UK operators but they offer a similar sort of rate so I am not trying to single out O2 and/or Vodafone.

Since LTE is 'All-IP' network my interest is more from Data point of view rather than the voice point of view. A colleague who went to India recently decided that enough is enough and he bought a SIM in India locally. Apparently is just a bit too difficult to get SIM in India if you are not an Indian resident, nevertheless he somehow managed it. The rates as shown below was INR 24 for 100 MB of data.

Rs. 24 is something like $0.50 or £0.35. You see my problem regarding the data rates? People may be quick to point out here that India has the cheapest data rates in the world. On the other hand we look at US, the rates are as follows:

Even if we assume $15 / 1GB data, its far cheaper than the roaming rate which may be something like, £3/MB = £3000/GB or £6/MB = £6000/GB.

I blogged about all the interesting developments that have been happening in LTE World Summit regarding the roaming solutions but what is the point of having all these solutions if the operators cant work out a way to reduce these costs. Or is it that they do not want to reduce these costs as they are a good source of income?

The operators complain that the OTT services are taking business away from them and turning them into dumb data pipes but to a lot of extent its their fault. People like me who travel often dont want to spend loads of cash on data and have worked out a way around it. Most of the places I visit have WiFi, most of my work is not urgent enough and I can wait till I am in a WiFi coverage area. In some parts of the world, still I have to buy an expensive WiFi access but compared to the roaming rates, its still cheap so I have stopped complaining about it. My decision to book a hotel depends of reviews, free breakfast and free WiFi. Some of our clients who give us their phone to use abroad strictly inform us that data should not be turned on unless its a matter of life and death.

If the operators dont change their strategies and work out a better solution for the roaming rates I am afraid that their short term gains will only lead to long term pains.

Monday, 22 April 2013

Its been a while since I last posted something on eMBMS. Its been even longer that we saw anything official from 3GPP on eMBMS. Recently I have seen some operators again starting to wonder if eMBMS makes business sense, while the vendors and standards are still working hard on the technology.

Not so long back, HEVC/H.265 codec was standardised. This codec helps transmission of the video using half the bandwidth. This means that it would be economical to use this for broadcast technologies. No wonder Nokia, Thompson and NTT Docomo are excited.

Interesting picture from a Qualcomm presentation (embedded in the end) shows how different protocols fit in the eMBMS architecture. My guess would be that the HEVC may be part of the Codecs.

On the operators front, Korea Telecom (KT) has intentions for countrywide rollout. Korea is one of the very few countries where end users have embraced watching video on small form factors. Verizon wireless has already signalled the intention to rollout eMBMS in 2014; its working out a business case. Telenor Sweden is another player to join the band with the intention of adopting Ericsson's Multi screen technology.

One of the main reasons for the lack of support for the 3G MBMS technology was not a compelling business case. Qualcomm has a whitepaper that outlines some of the potential of LTE Broadcast technology here. A picture from this whitepaper on the business case below:

Finally, a presentation from Qualcomm research on eMBMS embedded below:

Tuesday, 30 October 2012

We had quite a few interesting discussions in the Small Cells Global Congress, Operator Mindshare session. Here are some of the things that were discussed:

Licensed v/s Unlicensed deployments:

Many operators are now deploying WiFi in the unlicensed spectrum. This can help in the short term to alleviate the capacity problems but as more and more of this unlicensed spectrum nodes get deployed, they create interference between each other and make them unusable for anyone. An example was provided about Tokyo where in some areas, too many free WiFi hotspots means its unusable for anyone. One solution is to have one operator do all the logistics for the deployment and other operators can pay to use the service. Who (operator) would be the first one to go through the process of deploying everything first? Everyone would prefer wait and watch approach.

Providing free WiFi:

The consensus was that the free WiFi provided by operators don't give any additional benefit to them and there isn't much of a business case.

Consumer awareness for residential Femtocells:

Globally, not much effort is being done by the operator to make the end users aware of residential Femtocells and this is hampering the take-up A point was made about when Vodafone launched their product, Vodafone Access Gateway (VAG), it was perceived as negative thing because the ads show that if the coverage was poor you can install this to improve coverage. From a users perspective, it showed that the network had poor coverage. Still consumer awareness is important, how to do it?

Placement of Small Cells:

Where should the public small cells (metrocells) be placed. The Biggest challenges are:

* Site Acquisition is the biggest problem. - This is a bigger problem if lap posts are sought to deploy on public locations

* Rent

* Planning

* Installation

* Power - Lamp posts are centrally switched off, so small cells on laamp posts may need alternative sources

* Power meter if used in a shared location

* Bullet proof (especially in the US)

* Backhaul - especially is non line of sight case.

* Health concerns (if visible)

* Visual appearance

* Opex

Backhaul:

Operators should be clearer in what they want. Right now the vendors are pushing the solutions that operators not necessarily need and not giving what the operators want. The Backhaul should be more flexible and future proof. It should be able to cater for upcoming technologies like Carrier Aggregation, CoMP, etc.

Shared v/s Dedicated carrier for 3G Small Cells:

Dedicated carrier is ideal but is not easily possible for most operators. When shared carrier is used it causes interference and handovers are not easy.

Interoperability in the new hardware equipment for support of small cells:

Certain vendors are still not creating the the networks that can interwork with other vendors equipment. As we are moving towards LTE, this seems to be a much bigger problem. Sprint for example has 3 completely different networks in the US with no interoperability between them. Standards are not helping either as they do not dictate implementation.

Some Interesting discussions on Case studies, Business Cases, etc.

Mosaic Telecom:
* Deployed residential Femtocells
* Deployed for coverage purpose
* Dont have handover capability yet
* Want to be able to deploy Microcells/Small Cells on Highways, around 1-2Km radius
* Their typical Microcells use 40W output power
* The cost of deployment if Macro using cabinet, antenna, etc is roughly 100K per site.

Telefonica, O2 trials in UK
* To get access to council lamp posts, it was required that the bidder offer free WiFi
* O2 set a high bar by paying lot of money to the councils in London, but this is not a sustainable model

A Business case for carrier neutral WiFi on light pole in Lima, Peru
* Each light pole can have 3 different locations
* The retail business case is to get the user to usse the offering and maybe offer the operator services, tempting to move to this operator from current one
* There can be a wholesale case of selling the WiFi capacity in bulk to companies, organisations

Some interesting statistics thrown up:

* WiFi cell radius is 30m in South America

* 83% of people in US think that operators should provide free WiFi because of lousy coverage of the mobile network.

* The first 4000 customers of a WiMax operator were using an average of 750 MB per day, 22.5GB per month.

* Some fixed Internet operators are now thinking of putting a cap on unlimited offering at 350GB per month.

There were no consensus and conclusions for many items so feel free to write your opinion in the comments.

The last table is from an Ofcom document here. Its very interesting read. For example I didnt know that The L-band was the first major part of Ofcom spectrum awards programme relevant to mobile services. It consists of 40MHz between 1452MHz and 1492MHz. The auction took place in May 2008, in which Qualcomm won the entirety of the available spectrum.

Here is the summary of the operators working on LTE:

Everything Everywhere (EE = Orange + T-Mobile) - They are calling their '4G' service as EE, covering up to 70% of the UK by the end of 2013. Network kit provided by Huawei.

Three - Samsung will provide the Radio Access Network, and the core infrastructure, for Three's LTE (4G) network. That includes the base stations, and radio core. 3 UK has agreed to purchase 2 x 15 MHz of 1800 MHz spectrum from Everything everywhere, and plans commercial launch of LTE service in 2013.

Telefonica (O2) trial network - Equipment supplied by Nokia Siemens Networks (NSN) for both the Radio and Core network elements. Backhaul for the 4G trial network has been provided using Microwave Radio Equipment from Cambridge Broadband Networks Limited, NEC and Nokia Siemens Networks.

Updated 13/09/12 - 11:25

UK Broadband rolled out the first commercial TD-LTE network in London back in February (available to customers since May 2012). The equipment is provided by Huawei. They have 40MHz in Band 42 (3.5GHz) and 84MHz in band 43 (3.6GHz).

Wednesday, 13 June 2012

The 4th Future of Wireless International Conference (#FWIC) is 2 weeks away and the main theme of the conference is "The Reshaping of the Mobile Industry". In some of the recent conferences I have attended, OTT has been one of the main topic of discussion and a concern for the operators. The operators are at the top of the food chain, whatever affects them eventually affects the other players within the mobile industry. With this is mind, we have prepared a document that collects all the figures in one place to be used as a handy reference for quoting stats and figures.

Thursday, 19 April 2012

Access Point Name (APN) identifies a packet data network (PDN) that is configured on and accessible from the packet core (eg. GGSN). APNs are similar to a DNS name of the packet core and its composed of 2 parts.

• The APN Network Identifier which defines the external network or service that the user wishes to connect to via the packet core.
• The APN Operator Identifier which defines in which mobile network the packet core is located.

The APN that a mobile user is allowed to use is either programmed in the phone, or it could be sent over the air (OTA) via SMS. If an invalid APN is used then the PDP context request would be rejected with Invalid APN cause.

The networks of today are capable of handling any APN name and in fact recently I read some operator will allow any APN name to be used (PS: I cant remember details so please feel free to add link in the comment if you know). The reason for any APNs is that users use mobiles that were used on other networks which would have their APN settings, so the operator allows them to use any APN and then send OTA message to provide new settings.

The problem starts on these devices of today, even though you may say that you dont want to use operator data (especially while roaming), it still uses data and if the user does not have a good data plan then he may end up running a huge bill. See a discussion on this topic here and here.

From operators point of view, once they have sent setting OTA then they dont send it again. The users have come up with a workaround that they can use an invalid APN name and that would not connect to the operators network and incur data costs. The problem is that since the PDP Context request was now rejected, the device retries it when the device tries to use data again (mostly when there is no WiFi due to user being out and background apps are still running). This can cause loads of unnecessary signalling (for establishing PDP context).

In a situation like this, Martin Prosek from Telefonica, Czech Republic, mentioned that they have introduced 'PDP Context Parking'. They accept the PDP context request even though the APN is invalid but redirect the user to a default page where the user has many options like name of correct APN for someone using wrong APN by mistake, possiblity to buy 'bolt-ons' so they can use data over the mobile network and in some cases simply some free data allowance so that the users can get a feel of mobile data usage. This helped Telefonica O2, Czech Republic, reduce signaling and improve pdp connection success rate

I think this is a great idea and if someone has more information on this or personal experience, please feel free to add.

From the ETSI leaflet (note that this is quite old information but still on the ETSI website here):

IMS interoperability is a key issue for boosting IMS (IP Multimedia Subsystem) roll-out and more specifically network interconnection between operators. Only through thorough testing in practical scenarios can operators ensure operational excellence in a multi-vendor and multi-provider environment.

IMS comprises a set of specifications designed to enable network operators to implement IP-based networks that can carry services for both fixed and mobile customers simultaneously.

IMS was developed originally in the mobile world (specifically in the specifications created by the 3rd Generation Partnership Project, 3GPP), and was adopted for fixed networks by ETSI’s TISPAN Technical Committee (Telecoms & Internet Converged Services & Protocols for Advanced Networks).

However this promise of advanced communications over the next generation network will only be delivered if those same networks can interconnect.

ETSI’s Technical Committee INT: IMS Network Testing

ETSI is bridging the existing gap between 3GPP IMS Core Network standards and the initial industry IMS implementations through the organization of IMS interoperability events in connection with ETSI’s Centre for Testing & Interoperability (CTI) and Plugtests™ interoperability testing service.

Our Technical Committee for IMS Network Testing (TC INT) is actively establishing close contact with a number of industry fora and organizations dealing with IMS interoperability, including 3GPP, GSMA, MSF (Multi Service Forum), IMS Forum and the ITU-T. TC INT develops IMS test specification according to conformance, network integration and interoperability testing methodologies. Other ongoing work includes development of tests for Supplementary Services based on regulatory requirements and IMS tests with legacy networks (e.g. SIP-I).

ETSI has already held two IMS interoperability events. The first examined interconnection aspects of 3GPP IMS Release 6, including such issues as basic call on the Mw interface. The second event had a wider scope that included the testing of 3GPP IMS Release 7 interworking, roaming, border control, and integration of application servers executing selected Multimedia Telephony supplementary services.

Future ETSI activities and events will go even deeper towards bridging 3GPP IMS standards and industry implementations. These will include the organization of further IMS interoperability events designed to boost the roll-out and take-off of IMS services and operators’ network interconnections.